Method of manufacturing metal tubing



R E A B l L METHOD OF MANUFACTURING METAL TUBING Filed July 15, 1927INVENTOR. 60 db/m Bayer.

BY A TTO/PNE).

Patented May 14, 1929.

UNITED STATES LEO JOHN BAYER, OF ST. LOUIS, MISSOURI.

METHOD OF MANUFACTURING METAL TUBING.

Application filed July 15, 1927. Serial No. 206,004.

The present invention has relation to improvements in the methods ofmanufacturing metal tubing, and it consists in the noyel features morefull set forth in the spec1fication and pointe out in the claims.

My improved tubing is particularly adapted to withstand the corrosiveeffects of furnace gases and is for use, therefore, primarily in sootblowers or other apparatus in connection with boilers which are exposedto the furnace gases.

The rincipal object of the invention is to provide a tube having theproperty above pointed out, at a low cost, and by a method that issimple. I have found that this can best be done by combining an ordinaryrolled steel tube with a thin sheath of chromium steel to form acomposite tube. Thus the advantage of the corrosion re- 2o-sistingproperties of the chromium steel are obtained only on the outer surfaceof the composite tu where needed. The cost of the composite tube is muchless than an all chromium alloy tube, and the difliculties offabricating-an all chromium alloy tube are avoided.

Further advantages will be better apparent from a detailed descriptionof the invention in connection with accompanying drawings, in which Fire 1 is a side elevation of a piece of soot lower tube, or element, madeaccord ing to the teachings of this invention; Fig. 2 IS an enlarged lonitudinal section taken on a medial plane 0 a piece of the blower tube;Figs. 3 and 4 are vertical cross-sections taken on the line 3-3 and 4--4respectively of Fig. 1; Fig. 5 is a develop ment of oneof the sectionsof sheathing encasing the ordinary tube and Fig. 6 is an edge view ofsaid section before being rolled into a tube.

Referring to the drawings, T represents a piece of soot blower elementcomprising an ordinary steel tube 1 with a plug 2 Welded into one end,and a chromium alloy steel sheathing S enveloping said tube 1. Steamnozzles 3 (pass through the sheathing and are welde or otherwise securedinto the tube 1.

The sheathing S comprises a plurality of telescopin cylinders 4, 4 etc.,each of which is rolled rom a blank a, the side edges 5, 5 of which arebent over and the corners 6, 6

5 at one end cut out, as shown in Fig. 6.

then the blank (I is rolled into a cylinder the edges 5, 5 are broughttogether to form a lock-seam 7 and the cut out corners 6, 6 form a notch8. After the blanks have been rolled into cylinders the end 9 havin thenotch 8 is spread or swaged suflicient ly so that it will receive theopposite end of a similar cylinder. Obviously the presence of the notch8 instead of the seam 7 at one end of the cylinder 4 enables this end tobe easily spread and at the same time provides a recess to receive theend of the next adjacent cylinder or section.

The cylinders 4 are of a diameter compared to the tube 1, that they willjust slide over said tube. Preferably there should be no appreciablespace between the tube and sheathing. The chromium content of the steelfrom which the blanks a are stamped is not critical, but may be anywherebetween 15% and 35%. Then, too, some other steel alloy may be used withequal advantage if it possesses the property of resisting corrosion andoxidation when exposed to the action of hot furnace gases.

If the entire blower element were made of chromium alloy steel it wouldnecessarily have to be of a thickness that would render it difiicult toroll. On the other hand, mere- 1y providing the blower tube with a thin85 sheathing enables one to roll even a high chromium content alloy withcomparative ease. In this manner I provide a blower element havinglastin qualities equal to those of an element Ina e entirely of chromiumalloy at a greatl reduced cost.

Having descri (1 my invention, I claim:

1. The method of fabricating elements for soot blowers, which consistsin rollin thin blanks of non-corrosive and non-oxidizing steel alloyinto cylinders, spreading one end of each cylinder 'sufliciently toreceive the unspread end of another cylinder, sliding a plurality ofsaid cylinders over an ordinary steel tube and causing adjacentcylinders to 100 be joined in telescopic relation.

2. The method of fabricating elements for soot blowers, which consistsin rollin thin blanks of non-corrosive and non-oxi izing steel alloyinto cylinders, forming the abut- 105 ting ends of each cylinder into aseam, cutting out the seam at one end of each cylinder to form a notch,spreading the notched end of each cylinder sufficiently to receive theunspread end of another cylinder, s1id- 110 and causing the adjacentcylinders to be intimately connected, (perforating the com- 1 positietube and cylin er, and fixing a nozzle in the perforation of the tube.

In testimony whereof I hereunto aflix my signature.

LEO JOHN BAYER.

